Relative effectiveness of animated and static diagrams: An effect of learner prior knowledge

This paper investigates the relationship between instructional effectiveness of animated vs. static diagrams and levels of learner expertise in the task domain of transforming graphs of simple linear and quadratic functions. It was demonstrated on many occasions that instructional formats that are effective for low-knowledge learners could be ineffective, or even deleterious, for high-knowledge learners, and vice versa (the expertise reversal effect). The levels of learner (university students) expertise in this study were measured using an online rapid diagnostic method, a rapid verification technique, that involves presenting learners with a series of possible solution steps reflecting various stages of the solution procedure and asking them to rapidly verify the suggested steps. The results indicated a significant interaction between levels of learner expertise and instructional formats. Novice learners benefited more from static diagrams than from animated diagrams, while more knowledgeable learners benefited more from animated rather than static diagrams. A theoretical explanation of the effect is suggested within the framework of cognitive load theory.     

Sampled fictitious play for approximate dynamic programming

Sampled fictitious play (SFP) is a recently proposed iterative learning mechanism for computing Nash equilibria of non-cooperative games. For games of identical interests, every limit point of the sequence of mixed strategies induced by the empirical frequencies of best response actions that players in SFP play is a Nash equilibrium. Because discrete optimization problems can be viewed as games of identical interests wherein Nash equilibria define a type of local optimum, SFP has recently been employed as a heuristic optimization algorithm with promising empirical performance. However, there have been no guarantees of convergence to a globally optimal Nash equilibrium established for any of the problem classes considered to date. In this paper, we introduce a variant of SFP and show that it converges almost surely to optimal policies in model-free, finite-horizon stochastic dynamic programs. The key idea is to view the dynamic programming states as players, whose common interest is to maximize the total multi-period expected reward starting in a fixed initial state. We also offer empirical results suggesting that our SFP variant is effective in practice for small to moderate sized model-free problems.     

Incorporating learner experience into the design of multimedia instruction.

In Experiment 1, inexperienced trade apprentices were presented with one of four alternative instructional designs: a diagram with visual text, a diagram with auditory text, a diagram with both visual and auditory text, or the diagram only. An auditory presentation of text proved superior to a visual-only presentation but not when the text was presented in both auditory and visual forms. The diagram-only format was the least intelligible to inexperienced learners. When participants became more experienced in the domain after two specifically designed training sessions, the advantage of a visual diagram-auditory text format disappeared. In Experiment 2, the diagram-only group was compared with the audio-text group after an additional training session. The results were the reverse of those of Experiment 1: The diagram-only group outperformed the audio–text group. Suggestions are made for multimedia instruction that takes learner experience into consideration. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Analytical modeling of the white-light fringe

An analytical technique for extracting phase, visibility, and amplitude information as needed for interferometric astrometry for the Space Interferometry Mission (SIM) is presented. This model accounts for a number of physical and instrumental effects and is valid for the general case of a bandpass filter. I was able to obtain a general solution for polychromatic phasors and to address the properties of unbiased fringe estimators in the presence of noise. For demonstration purposes I studied a rectangular bandpass filter with two different methods of optical path difference (OPD) modulation: stepping and ramping OPD modulation. A number of areas for further studies relevant to instrument design and simulations are outlined and discussed.     

False cyanide formation during drinking water sample preservation and storage

Carefully controlled bench-scale and on-site experiments demonstrated that cyanide can form in the treated drinking water sample container during preservation and storage. In the bench-scale experiment, treated tap water samples were collected on 20 days over six months. The tap water samples were split and some of the splits were spiked with formaldehyde, a known ozone disinfection byproduct, held for three hours and tested for cyanide. Then they were preserved and held for 2-10 days. None of the 69 initial samples had cyanide detects, but 22 of 49 formaldehyde-spiked samples and three of the 20 unspiked samples developed detectable cyanide concentrations during storage. In the on-site experiment, six samples were collected at a finished water tap at an ozone/chloramination treatment plant over three days. Each sample was split, and a portion was spiked with formaldehyde. Each portion was analyzed in triplicate after three different procedures: (1) immediately distilled on-site, (2) stabilized on-site in a distillation tube and distilled back at the laboratory several days later, or (3) following the conventional procedure of preserving the sample to pH > 12 in a container and distilling the sample back at the laboratory. Only the samples handled in the conventional way had detectable amounts of cyanide. Both experiments demonstrated that cyanide can form during conventional preservation and storage, and it is likely that the cyanide detected for this treated drinking water was formed in the sample container as a consequence of the preservation and storage conditions.